RT info:eu-repo/semantics/doctoralThesis
T1 Massive obscured clusters in the milky way.
A1 Rubke Zúñiga, Klaus Simón
K1 ESTRELLAS
K1 EVOLUCION ESTELAR Y DIAGRAMA HR
AB This thesis comprises of a full search in our galaxy for the hidden population of massive starsusing the near-infrared photometry with a novel method and a quantitative spectroscopy studyof an O star sample in the optical and near-infrared.Massive clusters are those with mass greater than 10^4 Solar Masses . The number of known massiveclusters is significantly lower than the real prediction, as in general, due to the gas and dust thatsurround those clusters make diffcult to find them in the optical range and due to it is necessaryto use near infrared to find and observe them.Under the MASGOMAS (MAssive Stars in Galactic Obscured MAssive clusterS) project,the main objective of this thesis is to find massive stars using 2MASS photometry on the northdisc of the galaxy, using LIRIS@WHT (William Hershel Telescope) as the main telescope tomake the follow-up.The method that we used to find the candidates for the massive stars was to develop an automaticdetection algorithm, which mainly using photometric cuts (K , (J-K) and QIR), which eliminatea large part of the late not-massive population, and an overdensity algorithm over the starswhich fulfill the photometric cuts. From this study is presented the association MASGOMAS-6, that result in two populations at two di erent distances. To find high probability massivecluster candidates, we have developed a study that critically improves the way to select the overdensities.As result of this improvement we present the association MASGOMAS-10. In bothassociations the massive star population is confirmed, supporting the automatic method.The second part focused on the quantitative spectroscopy study of 12 O-type stars with highresolution optical spectra (R ~ 46000), which are also present in a survey of high resolution inthe near-infrared (R ~ 12000). To estimate stellar parameters we use the IACOB Grid-BasedAutomatic Tool (IACOB-GBAT), an accurate and fast method that compares, by means of a chi^2algorithm, observed and synthetic H and He line profiles in an automated way. Deriving theoptical stellar parameters we test the viability of deriving parameters using only near-infrared.This study also lead us to study the not well know clumping condition for our sample, creatingtwo full grids of clumping modelsFinally the clumping study results in a drastic improvement for several wind lines, especiallyfor supergiant stars.
YR 2017
FD 2017
LK http://riull.ull.es/xmlui/handle/915/24557
UL http://riull.ull.es/xmlui/handle/915/24557
LA en
DS Repositorio institucional de la Universidad de La Laguna
RD 17-may-2024